I go to a small (but respected) liberal arts college. I am a third year majoring in Mathematics and Creative Writing. I also have a great deal of passion for Linguistics. Particularly grammar and syntax (and how those topics relate to mathematics).

Because I'm already working with mathematics and many topics found in linguistics (especially because of my creative writing major), I figured that maybe I could try and shoot for a bi-disciplinary major involving math and linguistics. It wouldn't be too many extra classes, maybe?

The tricky part is that my college only offers an associate's degree in Linguistics. It does not have a full four-year program.

What can I do, or rather, what can I focus on, and what classes could I take, to make successful my pitch for some kind of computational linguistics bi-di degree? I know this is a very open ended question, so if y'all are willing to kind of conversate through it, I'm more than happy to, as well.

I'm also a student at a small but respected liberal arts college, though I and some others I've helped have jumped through the hoops of odd study programs, so I'll take a swing.

Probably obvious, but have you checked the official policies of your school and/or talked to a professor who may be on board to aid you? You'll almost certainly need someone in an official position to be approving the design of your individual program. Also keep in mind while majors are nice and all, unless you have a specific need for an official document saying you majored in linguistics, just taking classes isn't a terrible option. It'll be on your transcript and nothing stops you from mentioning them. Or, if you take several, some sort of minor may be feasible. Late in the game, but if you have room in your schedule, most places only require 5-6 classes. Even if no minor is offered, an individualized sort of minor may be easier to swing than a unique bi-disciplinary major.

Without knowing what classes your school offers I only have general ideas, but when I was considering a similar route (logic, which as you are possibly aware has some ties to linguistics, especially the computational sort), I looked at classes in linguistics (duh), AI (in CS), natural language computation (also CS), logic (math/philosophy), and philosophy of language. As far as I know, when you look at the intersections of math and linguistics you end up in the land of CS and logic rather frequently. Also some statistics wouldn't hurt to look into. If you do some asking around people in those departments at your school will probably have specific suggestions.

I will tell you frankly that a Linguistics degree is only nice to have if you treat it as a complement to a math / computer science / chemistry / biology major. Why? Theoretical Linguistics plays almost no role in the industry today, so that means you would be restricted to academic positions, which means getting a PhD. Theoretical linguists are getting outpaced by their computational counterparts.

Linguistics is a great complement to the majors I listed above because it opens many doors that combine those two fields.

So I would not lament about not being able to major in Linguistics. A breadth study is all that's needed, unless you desire to get a PhD / go into academia. In that case, I would suggest a master's program in Linguistics after undergraduate, then do a PhD. But don't do the master's if it will cost you your neck and leg.